The higher end of the electromagnetic frequency spectrum (e.g., 20 megahertz (MHz) to 4.times.10.sup.8 MHz) has received a large amount of attention in recent years for use in a variety of applications in the fields of communications, sensors and imaging. This portion of the electromagnetic frequency spectrum includes radio frequency (RF) signals, microwave signals, infrared signals, and optical (i.e., laser) signals. Because of the lack of naturally existing sources of radiation within these frequency bands and the relatively recent development of the technology that can operate in this portion of the electromagnetic frequency spectrum, devices operating in these frequency ranges are desirable for a wide variety of applications, including military and commercial.
Devices that comprise detectors which operate in these frequency ranges can be used to, inter alia, determine the direction and range of incident radiation signals. For example, using relatively simple and well known formulations, two or more sensors can be used in combination to determine the incident angle (also referred to as bearing) of a received signal by comparing the relative signal strengths of the respective sensors. Further, two or more such paired detectors spaced apart at a known distance can be utilized to determine the range to the source of the signal by using the method of triangulation.
An example of an infrared radiation detector that may be able to determine the direction of a radiation signal is disclosed in U.S. Pat. No. 4,769,531 to Fritz J. Malek, entitled "Directional Finder System with Inclined Detectors" (hereinafter referred to as "Malek"). In Malek, four detectors are positioned about the Z axis so as to face the Z axis at an incline. An associated computer processes the received signals and computes a direction of the incident signals. However, systems such as the one disclosed in Malek are relatively large and are not self-aligning. Further, with specific regard to Malek, the detector configuration disclosed apparently requires a frame to support the radiation receiving surfaces which significantly increases the complexity, and therefore cost, of fabrication.
While current radiation detectors are useful for many applications, there are a vast number of applications in which miniaturized devices on the scale of microelectronic devices are desirable, if not required. In fact, there exists an ever present desire to miniaturize signaling devices in order to, among other things, reduce cost, reduce power consumption, and increase packaging density. Current microelectronic radiation devices are generally planar because of the necessity to fabricate these devices using known microfabrication techniques such as photolithography, masking, etching, etc. See, for example, U.S. Pat. No. 5,030,828 to Solomon, entitled "Recessed Element Photosensitive Detector Array with Optical Isolation" (hereinafter referred to as "Solomon"), and U.S. Pat. No. 5,583,058 to Utsumi et al., entitled "Infrared Detection Element Array and Method for Fabrication the Same" (hereinafter referred to as "Utsumi et al."). The devices disclosed in Solomon and Utsumi et al. are planar devices, and therefore, typically require a relative large detection device to attain sufficient angular resolution.
Thus, a heretofore unsatisfied need exists in the industry for a microelectronic radiation detector that is sized on the scale of microelectronic devices and is capable of spatial detection.